Study of the failure of condenser tube in water cooled centrifugal chiller

Abstract

Centrifugal Chiller is the most essential component of district cooling system. Intricate electromechanical design of the chiller leads to certain unanticipated and unpredictable failures, which affect the overall operational efficiency and reliability of the plant. A case study of unusual type of failure in centrifugal chiller serving district cooling plant has been discussed and presented in this paper. The main purpose of the study is to evaluate the underlying cause of failure of condenser tube. The study takes all possible failure assessments into consideration starting from visual inspection through hardness test, down to x-ray diffractometry. The end of the study demonstrates that the condenser tube leakage is principally attributed to impingement of miniature high velocity water jet at the small region inside the tube which removes the protective copper oxide film, thereby, making that area susceptible to corrosion. Entrapped vibrating foreign wire-like body with free end grinding against interior wall of the copper tube causes a similar damage to the protective film at the same area. Both effects resulted in a rarely reported type of erosion-corrosion phenomenon which finally causes the tube failure.